{% extends "header.html" %} {# <html><body> #} 
{% block title %}{% if title %}{{ title }}{% else %}404 Not Found{% endif %}{% endblock %}
    {% block content %}
    <h1>Error: {% if error %}{{ error }}{% else %} 404 - File Not Found{% endif %}</h1>
    <p>The url you used is not accessible. check again. Alternatively, you can go to the <a href="/">Home Page</a> or use the navbar above to go to some other page. </p>
    {% endblock %}
  {# </body></html> #}